Method and Apparatus to Detect the Alignment of a Substrate

Abstract

A method of detecting the alignment of a substrate during a sequence of printing steps, comprises detecting in a detection unit a position of at least one printing track that forms a printed pattern onto a surface of the substrate in a first printing station, determining a reference point in at least a portion of the printing track, comparing the actual position of the reference point with an expected or previously detected position of the reference point, determining an offset between the actual position and the expected or previously detected position of the reference point, adjusting the reciprocal position between the printing head of a second printing station and the substrate to account for the determined offset, and then printing a second pattern over the first pattern.

1 - 13 . (canceled) 
     
     
         14 . A method of aligning a position of a substrate during a printing process, comprising:
 depositing one or more print tracks in a first pattern on a surface of the substrate, wherein the one or more print tracks comprises one or more reference points;   detecting a reference position of the one or more reference points on the surface of the substrate;   transferring the substrate to a printing position in a printing station;   comparing the printing position of the one or more reference points with an expected position within the printing station or the detected reference position of the one or more reference points;   determining an offset between the printing position of the one or more reference points and the expected position or the reference position;   moving the substrate or a printing head within the printing station a distance equal to the offset; and   depositing one or more print tracks in a second pattern on the surface of the substrate after moving the substrate using the printing head.   
     
     
         15 . The method of  claim 14 , wherein the first pattern and the second pattern comprise a plurality of tracks of a conductor paste. 
     
     
         16 . The method of  claim 14 , wherein the first pattern comprises a plurality of tracks of substantially parallel fingers. 
     
     
         17 . The method of  claim 16 , wherein the second pattern comprises a plurality of busbars. 
     
     
         18 . The method of  claim 14 , wherein the second pattern disposed on at least a portion of the first pattern. 
     
     
         19 . The method of  claim 14 , further comprising:
 detecting the reference position of the one or more reference points on the surface of the substrate using a first detection station; and   detecting the printing position of the one or more reference points on the surface of the substrate using a second detection station.   
     
     
         20 . The method of  claim 14 , wherein
 the detecting the reference position of the one or more reference points on the surface of the substrate and the detecting the second position of the one or more reference points on the surface of the substrate are performed using a single detection unit.   
     
     
         21 . The method of  claim 20 , wherein the single detection unit comprises an identification member and a comparison member. 
     
     
         22 . The method of  claim 14 , wherein the one or more print tracks comprises conductive materials for collecting a portion of a current generated by solar cell devices formed using the substrate. 
     
     
         23 . The method of  claim 14 , wherein, according to the result of the comparison, the position of the substrate relative to the printing head is corrected and adjusted by use of the determined offset. 
     
     
         24 . The method of  claim 14 , wherein
 the substrate is a wafer used for forming photovoltaic cells,   the first pattern comprises print tracks substantially parallel to each other, and   the one or more reference points are formed at least by a part of the first pattern or the second pattern.   
     
     
         25 . The method of  claim 14 , wherein the one or more reference points comprise at least three reference points. 
     
     
         26 . An apparatus for processing a substrate, comprising:
 a first printing station configured to deposit a first print track on the surface of a substrate;   an identification member that is configured to detect the reference position of one or more reference points formed by at least a portion of the first print track;   a second printing station configured to deposit a second print track on the surface of the substrate; and   a comparison member having a camera that is configured to detect the printing position of the one or more reference points formed by at least a portion of the first print track or the second print track, and compare the printing position of the one or more reference points with an expected position or the reference position.   
     
     
         27 . The apparatus of  claim 26 , further comprising:
 a control unit adapted to compare a reference position of one of the one or more reference points on the surface of the substrate with a printing position of one of the one or more reference points on the surface of the substrate.   
     
     
         28 . The apparatus of  claim 27 , wherein the identification member and the comparison member are connected to the control unit. 
     
     
         29 . The apparatus of  claim 26 , wherein the identification member comprises a first video camera positioned over the substrate that is configured to determine the reference position. 
     
     
         30 . The apparatus of  claim 29 , wherein the camera of the comparison member comprises a second video camera, and the comparison member is configured to compare the virtual image data detected by the first video camera with an image of the substrate detected by the second video camera. 
     
     
         31 . An apparatus for processing a substrate, comprising:
 a control unit;   a first printing station coupled to the control unit, and configured to deposit a print track on the surface of a substrate; and   a detection unit coupled to the control unit, comprising:
 an identification member configured to detect the reference position of one or more reference points formed by at least a portion of the print track; and 
 a comparison member configured compare the reference position with an expected position to determine an offset.